Paired-beam transponder satellite communication

ABSTRACT

Systems and methods are described for paired-beam satellite communications in a flexible satellite architecture. Embodiments include one or more “bent pipe” satellites having multiple transponders for servicing a number of spot beams. Implementations include novel types of paired-beam transponders that communicatively couple gateway terminals and user terminals in different spot beams. Some implementations also include loopback transponders that communicatively couple gateway terminals and user terminals in the same spot beam. The transponders can use similar components, can provide for flexible forward-link and return-link spectrum allocation, and/or can provide other features. Certain embodiments further include support for utility gateway terminal service and/or redundancy (e.g., active spares) for one or more active components.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.15/432,491, filed on Feb. 14, 2017, titled “PAIRED-BEAM TRANSPONDERSATELLITE COMMUNICATION”, which is a continuation of U.S. applicationSer. No. 14/952,722, filed on Nov. 25, 2015, titled “PAIRED-BEAMTRANSPONDER SATELLITE COMMUNICATION,” which is a continuation of U.S.Application Ser. No. 13/843,333, filed on Mar. 15, 2013, titled“PAIRED-BEAM TRANSPONDER SATELLITE COMMUNICATION,” which claims thebenefit of and is a non-provisional of co-pending U.S. ProvisionalApplication Ser. No. 61/696,717, filed on Sep. 4, 2012, titled“PAIRED-BEAM TRANSPONDER SATELLITE COMMUNICATION,” all of which arehereby expressly incorporated herein by reference in their entirety forall purposes.

FIELD

Embodiments relate generally to satellite communications systems, and,more particularly, to paired-beam satellite communications.

BACKGROUND

A satellite communications system typically includes a constellation ofone or more satellites that links ground terminals (e.g., gatewayterminals and user terminals). For example, the gateway terminalsprovide an interface with a network such as the Internet or a publicswitched telephone network, and each gateway terminal services a numberof user terminals located in one or more spot beams. Some architecturespermit gateway terminals to service user terminals in their own spotbeam coverage area via “loopback” beams. Other architectures permitgateway terminals to service user terminals in other spot beam coverageareas. These and other satellite system architectures tend to havelimited flexibility in terms of spectrum utilization, gateway terminallocation, and other characteristics.

BRIEF SUMMARY

Among other things, systems and methods are described for paired-beamsatellite communications in a flexible satellite architecture.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is described in conjunction with the appendedfigures:

FIG. 1 shows a block diagram of an embodiment of a satellitecommunications system having a satellite in communication with multipleground terminals over multiple spot beams, according to variousembodiments;

FIG. 2 shows a partial satellite communications system with anillustrative loopback transponder, according to various embodiments;

FIG. 3A shows a partial satellite communications system with anillustrative paired-beam transponder, according to various embodiments;

FIG. 3B shows a partial satellite communications system with anotherillustrative paired-beam transponder, according to various embodiments;

FIG. 4 shows a simplified block diagram of an illustrative partialsatellite architecture having both loopback transponders and paired-beamtransponders, according to various embodiments;

FIG. 5 shows an illustrative architecture of a paired-beam transponderthat includes utility gateway support, according to various embodiments;

FIGS. 6A and 6B show two configurations of an alternate illustrativearchitecture of a paired-beam transponder that includes utility gatewaysupport, according to various embodiments;

FIGS. 7A and 7B show two configurations of an illustrative architectureof a loopback transponder that includes utility gateway support,according to various embodiments; and

FIGS. 8A and 8B show two configurations of an alternative illustrativearchitecture of a loopback transponder that includes utility gatewaysupport, according to various embodiments.

In the appended figures, similar components and/or features can have thesame reference label. Further, various components of the same type canbe distinguished by following the reference label by a second label thatdistinguishes among the similar components. If only the first referencelabel is used in the specification, the description is applicable to anyone of the similar components having the same first reference labelirrespective of the second reference label.

DETAILED DESCRIPTION

Embodiments operate in context of satellite architectures that includeone or more satellites (e.g., in different orbital slots) thatcommunicate with many ground terminals (e.g., gateway terminals and userterminals) via multiple spot beams. Design of the satellite architecturecan address various types of goals. One such goal is to increaseopportunities for frequency reuse. Accordingly, some implementationsselect geographic placement of gateway terminals, allow user terminalsand gateway terminals to use the same spectrum, and/or other employtechniques. Another such goal is to place gateways in reliablelocations, for example, where there is less precipitation on average andlittle interference. Accordingly, some implementations place gatewayterminals in locations that may be near user terminals or far from userterminals.

Still, at the time when the satellite architecture is being designed, anumber of uncertainties can impact the design. For example, it istypically uncertain which spot beams will need the most capacity (e.g.,where the most users will be and/or where the highest bandwidth usagewill occur), how the spot beams will be used (e.g., the ratio offorward-link versus return-link traffic), etc. These uncertainties canimpact spectrum utilization. Accordingly, implementations of thesatellite architecture are designed to permit flexibility in spectrumutilization. For example, the satellite or satellites in thearchitecture can communicate with both gateway terminals and userterminals over the same spectrum at the same time, and varioustechniques can be used to allocate portions of that spectrum forforward-link and return-link traffic.

Embodiments include one or more “bent pipe” satellites having multipletransponders (e.g., and corresponding feeds) for servicing a number ofspot beams. Some transponders are paired-beam transponders thatcommunicatively couple gateway terminals and user terminals in differentspot beams. Some embodiments also include loopback transponders thatcommunicatively couple gateway terminals and user terminals in the samespot beam. In some implementations, the paired-beam transponders andloopback transponders use similar components, which can, for example,simplify the satellite design and facilitate other features (e.g.,certain types of component redundancy, etc.). Some embodiments alsoselectively facilitate utility gateway terminal service (e.g., in theevent of a gateway terminal outage). Certain embodiments further includetechniques for providing redundancy (e.g., active spares) for one ormore active components. Some such embodiments provide active spares incontext of also providing utility gateway functionality.

Turning first to FIG. 1, a block diagram is shown of an embodiment of asatellite communications system 100 having a satellite 105 incommunication with multiple ground terminals over multiple spot beams150, according to various embodiments. Embodiments of the satellite 105are designed as “bent pipe” satellites. The satellite 105 cancommunicate with the ground terminals according to any suitablecommunications architecture, such as a hub-spoke architecture. In someimplementations, some ground terminals are in substantially fixedlocations (e.g., at a residential or enterprise subscriber's premises),and other ground terminals are mobile terminals. Further, the term“ground” is used herein generally in contrast to the portions of thenetwork in “space” (i.e., the satellites 105). For example, embodimentsof the ground terminals can include mobile aircraft terminals and thelike.

For the sake of illustration, three spot beams 150 are shown havingdifferent compositions of ground terminals. A first spot beam 150 acovers an area including both a gateway terminal 165 and multiple userterminals 110 (typically many, though only three are shown for clarity).A second spot beam 150 b covers an area that includes only userterminals 110, and a third spot beam 150 c covers an area that includesonly a gateway terminal 165. Gateway terminals 165 can perform variousfunctions, such as scheduling traffic to user terminals 110,synchronizing communications with one or more satellites 105, codingand/or modulation (and decoding and/or de-modulation) of traffic to andfrom the satellite 105, etc. Some embodiments also include variousground segment or other systems. For example, geographically distributedbackhaul nodes are in communication with public and/or private networks(e.g., the Internet), with multiple gateway terminals 165 (e.g.,redundantly), and with each other via a high-speed, high-throughput,high-reliability terrestrial backbone network, and can can performenhanced routing, queuing, scheduling, and/or other functionality. Thevarious ground segment components can be communicatively coupled via anysuitable type of network, for example, an Internet Protocol (IP)network, an intranet, a wide-area network (WAN), a local-area network(LAN), a virtual private network (VPN), a public switched telephonenetwork (PSTN), a public land mobile network, a cellular network, and/orother wired, wireless, optical, or other types of links.

Each gateway terminal 165 and user terminal 110 can have an antenna thatincludes a reflector with high directivity in the direction of thesatellite 105 and low directivity in other directions. The antennas canbe implemented in a variety of configurations and can include features,such as high isolation between orthogonal polarizations, high efficiencyin the operational frequency bands, low noise, and the like. In oneembodiment, a user terminal 110 and its associated antenna togethercomprise a very small aperture terminal (VSAT) with the antenna having asuitable size and having a suitable power amplifier. Some embodiments ofgateway terminals 165 include larger antennas with higher power thanthose of the user terminals 110. In other embodiments, a variety ofother types of antennas are used to communicate with the satellite 105.

Each antenna is configured to communicate with the satellite 105 via aspot beam 150 (e.g., a fixed-location beam or other type of beam). Forexample, each antenna points at the satellite 105 and is tuned to aparticular frequency band (and/or polarization, etc.). The satellite 105can include one or more directional antennas for reception andtransmission of signals. For example, a directional antenna includes areflector with one or more feed horns for each spot beam. Typically, thesatellite communications system 100 has limited frequency spectrumavailable for communications. Contours of a spot beam 150 can bedetermined in part by the particular antenna design and can depend onfactors, such as location of feed horn relative to a reflector, size ofthe reflector, type of feed horn, etc. Each spot beam's contour on theearth can generally have a conical shape (e.g., circular or elliptical),illuminating a spot beam 150 coverage area for both transmit and receiveoperations. A spot beam 150 can illuminate terminals that are on orabove the earth surface (e.g., airborne terminals, etc.). In someembodiments, directional antennas are used to form fixed-location spotbeams (or spot beams that are associated with substantially the samespot beam coverage area over time). Certain embodiments of the satellite105 operate in a multiple spot-beam mode, receiving and transmitting anumber of signals in different spot beams (e.g., of the same ordifferent types). Each spot beam can use a single carrier (i.e., onecarrier frequency), a contiguous frequency range (i.e., one or morecarrier frequencies), or a number of frequency ranges (with one or morecarrier frequencies in each frequency range). Some embodiments of thesatellite 105 are non-regenerative, such that signal manipulation by thesatellite 105 provides functions, such as frequency translation,polarization conversion, filtering, amplification, and the like, whileomitting data demodulation and/or modulation and error correctiondecoding and/or encoding.

As used herein, the term spot beam 150 can generally refer to ageographic coverage area within a beam or the beams themselves. Forexample, a spot beam 150 can support one or more gateway uplink beams,gateway downlink beams, user uplink beams, user downlink beams, etc.Each type of beam may or may not support forward-channel andreturn-channel traffic. For example, in a hub-spoke configuration,forward-channel traffic travels from a gateway terminal 165 to asatellite 105 via a gateway uplink beam, and from the satellite 105 to auser terminal 110 via a user downlink beam; and return-channel traffictravels from the user terminal 110 to the satellite 105 via a useruplink beam, and from the satellite 105 to the gateway terminal 165 viaa gateway downlink beam. In some implementations, the different beamsuse different geographic locations, carrier frequencies, polarizations,communications timing, and/or other techniques to avoid inter-beaminterference.

A given beam can typically service many ground terminals. For example, a“user” beam can be used to service many user terminals 110, and a“gateway” beam can be used to service a gateway terminal 165 and anyuser terminals 110 in the coverage are of the beam. The various userbeams and gateway beams can use the same, overlapping, or differentfrequencies, polarizations, etc. In some embodiments, some or allgateway terminals 165 are located away from the user terminals 110,which can facilitate frequency re-use. In other embodiments, some userterminals 110 are located near some or all gateway terminals 165. Whilethe satellite communications system 100 can support very large numbersof ground terminals via large numbers of spot beams 150, only three spotbeams are shown for clarity.

As described herein, various implementations can exploit thisconfiguration of spot beams 150 and gateway terminals 165. For example,the gateway terminal 165 in the first spot beam 150 a can service userterminals 110 in its own spot beam 150 a via a “loopback beam” and/oruser terminals 110 in another spot beam (e.g., those in spot beam 150 b)via a “paired beam.” The gateway terminal 165 in the third spot beam 150c can service user terminals 110 in one or more other spot beams (e.g.,those in spot beam 150 a and/or spot beam 150 b) via one or more pairedbeams. For example, depending on the composition of ground terminals andthe type of communications employed by associated gateway terminals 165,a spot beam 150 can be a loopback beam, a paired user beam, a pairedgateway beam, etc. In some implementations, each gateway terminal 165includes two or more antennas to facilitate communications with multipletransponders on one or more satellites 105. Each antenna can supportcommunications on multiple frequency bands and/or polarities. Forexample, forward-channel uplink traffic can be sent on a first portionof an uplink frequency band in a first polarity, return-channel uplinktraffic can be sent on a second portion of the uplink frequency band ina second polarity, forward-channel downlink traffic can be sent on afirst portion of a downlink frequency band in the second polarity, andreturn-channel downlink traffic can be sent on a second portion of thedownlink frequency band in the first polarity. Allowing the gatewayterminals 165 and user terminals 110 to share the same spectrum canfacilitate frequency reuse.

FIG. 2 shows a partial satellite communications system 200 with anillustrative loopback transponder 210, according to various embodiments.For the sake of clarity, a single satellite 105 is shown incommunication with both user terminals 110 and a gateway terminal 165 ina single loopback beam 205 coverage area. The loopback beam 205 isconfigured so that the user terminals 110 and the gateway terminal 165share the same spectrum concurrently. This permits frequency reuseacross the ground terminals in the coverage area and allows schedulingfunctions (e.g., of the gateway terminal 165) to allocateforward-channel and return-channel capacity in a flexible (e.g., anddynamic) manner. Further, as described below, embodiments includesupport for a utility gateway via components of a utility supportsubsystem 290. For example, one utility support subsystem 290 canselectively couple a utility gateway, as needed, with multiple loopbacktransponders 210 (and/or paired beam transponders, as described below).

For example, the user terminals 110 and the gateway terminal 165 canconcurrently transmit uplink traffic to the satellite 105 via theloopback beam 205 at an uplink (or received (Rx)) frequency band, andthey can concurrently receive downlink traffic from the satellite 105via the loopback beam 205 at a downlink (or transmitted (Tx)) frequencyband. At each of the uplink and downlink frequency bands, a surroundingswath of frequency can be allocated flexibly to forward-channel andreturn-channel traffic. For example, each beam is allocated a frequencyband between about 27.5 and 30 Gigahertz as the uplink band and betweenabout 17.7 and 20.2 Gigahertz as the downlink band. Each of these2.5-Gigahertz bands can be further allocated in a flexible manner forforward-channel or return-channel traffic. For example, the resultingforward-channel and return-channel communications can share spectrumand/or power according to any suitable scheme, including, for example,by having allocated sub-bands of any suitable size (e.g., contiguous ornon-contiguous, overlapping or non-overlapping, adjacent ornon-adjacent, etc.), or by using spread spectrum or other techniques(e.g., code division, etc.).

Communications over the loopback beam 205 are facilitated by theloopback transponder 210. For example, communications from the userterminals 110 and the gateway terminal 165 are received by a satellitefeed 215 in communication with the loopback beam 205, processed by theloopback transponder 210, and transmitted back to the same userterminals 110 and gateway terminal 165 via the feed 215 (or another feedor feed port in communication with the loopback beam 205). The loopbacktransponder 210 can include any suitable receive and transmit componentsfor handling the loopback communications.

As used herein, a “feed” generally refers to the components forinterfacing the satellite 105 with a beam (e.g., loopback beam 205). Forexample, each feed can include an antenna, reflector, feed horn, etc. Insome implementations, each feed includes at least one transmit port andat least one receive port. For example, a feed can include an orthomodetransducer (OMT) or the like for receiving and transmitting at multiplepolarizations (e.g., right-hand circular polarization (RHCP) andleft-hand circular polarization (LHCP)), so that the feed includes atleast a first port for receiving at a first polarization, a second portfor receiving at a second polarization, a third port for transmitting atthe first polarization, and a fourth port for transmitting at the secondpolarization. Each transponder (e.g., loopback transponder 210) can bein communication with one of the receive ports and one of the transmitports (e.g., at opposite polarizations).

As illustrated, the loopback transponder 210 includes an input amplifier220, a down-converter 230, a channel converter 240, and an outputamplifier 250. Uplink traffic is received from the ground terminals bythe feed 215, processed by the input amplifier 220, down-converter 230,channel converter 240, and output amplifier 250 into appropriatedownlink traffic, and transmitted back to the ground terminals via thefeed 215. In some implementations, the input amplifier 220 is alow-noise amplifier (LNA) or the like. The input amplifier can includeany other suitable filters, attenuators, or other components tofacilitate receipt of traffic in a desired manner. The down-converter230 can convert the traffic received in the uplink band into traffic fortransmitting in the downlink band. For example, the down-converter 230effectively performs a 9.8-Gigahertz translation of the received signal(e.g., the 27.5-30 Gigahertz uplink traffic is translated to 17.7-20.2Gigahertz downlink traffic). Embodiments of the channel converter 240can perform various functions, such as frequency conversion relating tochannels having particular dedicated frequency sub-bands. The outputsignal can then be amplified as appropriate for communication back tothe ground terminals. In some implementations, the output amplifier 250includes a high-power amplifier (HPA), like a traveling wave tubeamplifier (TWTA) or the like. Other implementations of the loopbacktransponder 210 can include additional components without departing fromthe scope of embodiments.

For the sake of illustration, embodiments of loopback transponders 210,like those described with reference to FIG. 2, can be used to implementvarious methods. An illustrative method begins by receiving a gatewayuplink signal by a loopback transponder of the satellite from a firstgateway terminal via a loopback beam on an uplink frequency band. Asecond user uplink signal is received by the loopback transponder from agroup of user terminals via the loopback beam on the uplink frequencyband. The second group of user terminals is located in the same spotbeam coverage area as the first gateway. For example, the gateway anduser uplink signals can be received concurrently as a combined inputsignal in a non-coherent fashion. The combined input signal can beamplified and converted at to a combined output signal at a downlinkfrequency band that is different from the uplink frequency band. Thecombined output signal can be transmitted to the first gateway terminalvia the loopback beam on the downlink frequency band, and the combinedoutput signal can be transmitted to the group of user terminals via theloopback beam on the downlink frequency band.

FIG. 3A shows a partial satellite communications system 300 a with anillustrative paired-beam transponder 310 a, according to variousembodiments. For the sake of clarity, a single satellite 105 is shown incommunication with user terminals 110 in a first spot beam coverage areaserviced by a gateway terminal 165 in a second spot beam coverage areavia respective paired beams 305. As illustrated, the “paired beam”includes the beam over which the user terminals 110 communicate with thesatellite 105 (a “paired user beam” 305 a) and the beam over which thegateway terminal 165 communicates with the satellite 105 (a “pairedgateway beam” 305 b). Embodiments handle the paired beam 305 in asimilar manner as the loopback beam 205 described in FIG. 2. Forexample, though in two separate spot beams, the user terminals 110 andthe gateway terminal 165 can share the same spectrum concurrently,thereby permitting frequency reuse and flexible spectrum allocation.Further, embodiments of the paired-beam transponder 310 have a similararchitecture to that of embodiments of the loopback transponder 210.

For example, the user terminals 110 and the gateway terminal 165 canconcurrently transmit uplink traffic to the satellite 105 via theirrespective paired beams 305 at an uplink frequency band, and they canconcurrently receive downlink traffic from the satellite 105 via theirrespective paired beams 305 at a downlink frequency band. At each of thefrequency bands, a surrounding swath of frequency can be allocatedflexibly to forward-channel and return-channel traffic. In someimplementations, the spectrum is assigned similarly or identically tothe manner in which it is assigned in the loopback beam contextdescribed with reference to FIG. 2. Each of the assigned bands can beallocated in a flexible manner for forward-channel or return-channeltraffic.

Communications over the paired beams 305 are facilitated by thepaired-beam transponder 310 a. For example, communications from the userterminals 110 are received by a first satellite feed 215 a incommunication with the paired user beam 305 a, and communications fromthe gateway terminal 165 are received by a second satellite feed 215 bin communication with the paired gateway beam 305 b. The receivedcommunications are processed by the paired-beam transponder 310 a andtransmitted back to the same user terminals 110 and gateway terminal 165over their respective paired beams 305 via the respective feeds 215 (orother feeds 215 in communication with the paired beams 305). Thepaired-beam transponder 310 a can include any suitable receive andtransmit components for handling the paired-beam communications.

As in the loopback transponder 210 of FIG. 2, the paired-beamtransponder 310 a includes input amplifiers 220, a down-converter 230, achannel converter 240, and an output amplifier 250. Embodiments of thepaired-beam transponder 310 a further include an input combiner 325, anoutput coupler 355, an input attenuator 323, and an output terminator353. Uplink traffic is received from the ground terminals by therespective feeds 215; amplified by respective input amplifiers 220;combined by the input combiner 325 (and attenuated by the inputattenuator 323 as appropriate); further processed into appropriatedownlink traffic by the down-converter 230, channel converter 240,output amplifier 250, and output coupler 355 (with coupling gain asappropriate); and transmitted back to the ground terminals via therespective feeds 215.

Some implementations include a user-side input amplifier 220 a coupledwith a user-side feed 215 a, and a gateway-side input amplifier 220 bcoupled with a gateway-side feed 215 b. Each input amplifier 220 caninclude a low-noise amplifier (LNA) and/or any other suitable filters,attenuators, or other components to facilitate receipt of traffic in adesired manner. Typically, even if received on the same uplink band, theuser traffic and gateway traffic can differ in power, polarization, G/T(a measure of noise level received at the satellite in terms of thereceive antenna gain (G) and the system noise temperature (T)), etc.Accordingly, some implementations of the user-side input amplifier 220 aare identical or similar to implementations of the gateway-side inputamplifier 220 b, and may or may not be tailored to the particularcharacteristics of their respective received signals.

Embodiments of the paired-beam transponder 310 a combine the signalsreceived via the paired user beam 305 a and the paired gateway beam 305b (and amplified via their respective input amplifiers 220) using theinput combiner 325. The input combiner 325 can include a summer,directional coupler, hybrid coupler, and/or any other suitablecomponent. Some implementations combine the signals without additionalprocessing (e.g., attenuation). According to some implementations, thegateway and user signals are not coherent, so that they can be readilycombined.

Because the user and gateway signals typically have different respectiveG/T values, simply combining the signals can add noise to the combinedsignal (e.g., roughly three decibels of added noise in someimplementations). Accordingly, some embodiments include the inputattenuator 323 to provide more effective signal matching and combining.For example, attenuating the gateway-side signal prior to combining itwith the user-side signal can appreciably reduce the thermal noisecontribution from the gateway signal thereby improving thesignal-to-noise ratio of the user signal. The respective G/T values forthe user and gateway signals can be calculated according to thefollowing equations:

$( \frac{G}{T} )_{User} = {( \frac{G}{T} )_{{User}_{—}{Antenna}}*\frac{A}{1 + A}}$$( \frac{G}{T} )_{GW} = {( \frac{G}{T} )_{{GW}_{—}{Antenna}}*\frac{1}{1 + A}}$

where A is the attenuation provided by the input attenuator 323. Forexample, the input attenuator 323 can be configured to provide at leastfive decibels of attenuation to the gateway input signal.

The down-converter 230 can convert the combined signal into traffic fortransmitting in the downlink band. For example, the down-converter 230and channel converter 240 can perform frequency translation and/orfiltering functions, such as 9.8-Gigahertz translation of the receivedsignal, channel frequency sub-band conversion, etc. The output signalcan then be amplified as appropriate for communication back to theground terminals, for example, using a high-power amplifier (HPA), likea traveling wave tube amplifier (TWTA) or the like. Unlike in theloopback transponder 210 embodiments described above, the paired-beamtransponder 310 a prepares the combined and processed output signal forcommunication over the user-side feed 215 a and the gateway-side feed215 b using appropriate gains, etc.

In some embodiments, the output coupler 355 sends the output signal toboth feeds 215 and the coupling level can be selected to provide ahigher power version of the output signal to the user-side feed 215 athan to the gateway-side feed 215 b. In one implementation, the outputcoupler 355 is a passive coupler with a “through” port coupling theoutput of the output amplifier 250 with the user feed 215 a, and a“couple” port coupling the output of the output amplifier 250 with thegateway feed 215 b. An output terminator is coupled with an otherwiseunused input to the couple port. For example, a six-decibel outputcoupler 355 can apply approximately −1.25 decibel of gain to theuser-side downlink signal and can apply approximately −6 decibels ofgain to the gateway-side downlink signal. This allows the signal to beappropriately powerful for receipt by user terminals 110, which cantypically have smaller, lower power antennas (e.g., in fixed size, fixedpower terminals).

Embodiments of the transponders described herein can be considered asgenerally including an input subsystem 330, a frequency translationsubsystem 340, and an output subsystem 350. In the paired-beamtransponder 310 a of FIG. 3A, the input subsystem 330 includes the inputamplifiers 220, the input combiner 325, and the input attenuator 323;the frequency translation subsystem 340 includes the down-converter 230and the channel filter 240; and the output subsystem 350 includes theoutput amplifier 250 and the output coupler 355. Other implementationsof transponders, including other paired-beam transponders 310, caninclude additional components and/or the same components in differentorders or arrangements, without departing from the scope of embodiments.

FIG. 3B shows a partial satellite communications system 300 b withanother illustrative paired-beam transponder 310 b, according to variousembodiments. As described above, communications from the user terminals110 are received by a first satellite feed 215 a in communication withthe paired user beam 305 a, and communications from the gateway terminal165 are received by a second satellite feed 215 b in communication withthe paired gateway beam 305 b. The received communications are processedby the paired-beam transponder 310 b and transmitted back to the sameground terminals over their respective paired beams 305 via therespective feeds 215. FIG. 3B shows an input subsystem 330, a frequencytranslation subsystem 340, and an output subsystem 350. The frequencytranslation subsystem 340 and output subsystem 350 of FIG. 3B aresimilar or identical to those described with reference to FIG. 3A. Theinput subsystem 330 of the paired-beam transponder 310 b of FIG. 3Bincludes only one input amplifier 220 located prior to the inputcombiner 325 in the feeder path. For example, uplink traffic is receivedfrom the ground terminals by the respective feeds 215; amplified byrespective input amplifiers 220; combined by the input combiner 325;further processed into appropriate downlink traffic by thedown-converter 230, channel converter 240, output amplifier 250, andoutput coupler 355; and transmitted back to the ground terminals via therespective feeds 215. For the sake of added clarity, the descriptionfocuses only on the portions of FIG. 3B that differ from FIG. 3A.

Unlike in FIG. 3A, the paired-beam transponder 310 b is illustrated withits input combiner 325 prior to the input amplifier 220 in the inputsignal path. Combining the input signals prior to amplifying themmanifests certain differences as compared to the embodiments of FIG. 3A.One such difference is that the combined input signal can be amplifiedby a single input amplifier 220 in FIG. 3B, rather than using separateinput amplifiers 220 to amplify the separate input signals, as in FIG.3A. Another such difference is that the input combiner 325 of FIG. 3Boperates on the non-amplified, received signals, rather than operatingon the amplified input signals as in FIG. 3A. In one implementation, theinput combiner 325 is implemented as a passive coupler with its“through” port coupling the output of the user feed 215 a to the inputof the input amplifier 220, and its “couple” port coupling the output ofthe gateway feed 215 b to the input of the input amplifier 220. An inputterminator 343 is coupled with an otherwise unused output to the coupleport. For example, the input combiner 325 is implemented as asix-decibel passive coupler that applies approximately −1.25 decibels ofgain to the received user-side uplink signal and applies approximately−6 decibels of gain to the received gateway-side uplink signal. This caneffectively add approximately 1.25 decibels of noise to the user-sideuplink signal during the combination. Accordingly, as compared to FIG.3A, the implementation of FIG. 3B reduces hardware and complexity at theexpense of decreased G/T performance.

For the sake of illustration, embodiments of paired-beam transponders310, like those described with reference to FIGS. 3A and 3B, can be usedto implement various methods. An illustrative method begins by receivinga gateway uplink signal by a paired-beam transponder of a satellite froma first gateway terminal via a paired gateway beam on an uplinkfrequency band. The first gateway terminal is located in a first spotbeam coverage area. A user uplink signal is received by the paired-beamtransponder from a first group of user terminals via the paired userbeam on the uplink frequency band. The first group of user terminals islocated in a second spot beam coverage area that does not overlap withthe first spot beam coverage area. For example, the gateway and useruplink signals can be received concurrently in a non-coherent fashion.The gateway uplink signal and the user uplink signal can be amplifiedand combined into a combined input signal using the paired-beamtransponder (e.g., the amplifying can be performed before or after thecombining). The combined input signal can be converted to a combinedoutput signal at a downlink frequency band that is different from theuplink frequency band. The combined output signal can be transmitted tothe first gateway terminal via the paired gateway beam on the downlinkfrequency band, and the combined output signal can be transmitted to thefirst group of user terminals via the paired user beam on the downlinkfrequency band.

FIG. 4 shows a simplified block diagram of an illustrative partialsatellite architecture 400 having both loopback transponders 210 andpaired-beam transponders 310, according to various embodiments. Thecomponents for received and transmitting signals over the beams on thesatellite are generally abstracted as feeds 215 to avoidover-complicating the description. For example, as described above, thefeeds 215 can include antennas for reception and transmission ofsignals, each having a reflector with one or more feed horns for eachuser and/or gateway beam, and each having one or more ports forreceiving and/or transmitting using one or more polarities. In theillustrated embodiment, it is assumed that each feed 215 has up to fourports, including a first port for receiving at a first polarization(e.g., right-hand circular polarization (RHCP)), a second port fortransmitting at a second polarization (e.g., left-hand circularpolarization (LHCP)), a third port for receiving at the secondpolarization, and a fourth port for transmitting at the firstpolarization. Each of a number of transponders is coupled between feedports, so that, for example, a transponder receives signals from agateway at an uplink frequency band in a first polarization andtransmits signals to the gateway at a downlink frequency band in asecond polarization. In other implementations, the receive and transmitsides of the transponder operate in the same polarization. Theillustrated embodiment shows support for three gateway terminals 165communicating with user terminals 110 in six spot beam coverage areas.Each gateway terminal 165 is assumed to have an antenna that can supportcommunications in two polarities (e.g., RHCP and LHCP) with differentsets of user terminals 110. Accordingly, the satellite 105 includes twofeed ports to support communications with each gateway terminal 165.

In particular, as shown, a first port of a first feed 215 a- 1 and asecond port of the first feed 215 a-2 support communications between afirst gateway terminal 165 (“GW1” denotes the gateway terminal 165 onbeam 1) and user terminals in its own loopback beam coverage area (“U1”denotes the user terminals 110 on beam 1). The communications over theloopback beam are processed by a first loopback transponder 210 a. Forexample, communications from GW1 and U1 are received at the first portof the first feed 215 a-1 in RHCP, processed by the first loopbacktransponder 210 a, and transmitted back to GW1 and U1 in LHCP.

Remaining ports of the first feed 215 a and ports of a second feed 215 bsupport communications between the same first gateway terminal 165 via apaired gateway beam and user terminals 110 in a paired user beam (in adifferent coverage area, denoted as “U3”). The paired-beamcommunications are processed by a first paired-beam transponder 310 a.For example, communications from GW1 are received at the third port ofthe first feed 215 a-3 in LHCP, processed by the first paired-beamtransponder 310 a, and transmitted to U3 via the second port of thesecond feed 215 b-2 (e.g., in RHCP); and communications from U3 arereceived at the first port of the second feed 215 b-1 (e.g., in LHCP),processed by the first paired-beam transponder 310 a, and transmitted toGW1 via the fourth port of the first feed 215 a-4 in RHCP.

A second gateway (GW2) operates in much the same manner as GW1. Twoports of a third feed 215 c and a second loopback transponder 210 b areused to support GW2 communications with one group of user terminals 110(U2) in its own beam coverage area (i.e., via a loopback beam). Theother two ports of the third feed 215 c, two ports of a fourth feed 215d, and a second paired-beam transponder 310 b are used to support GW2communications with another group of user terminals 110 (U4) in a paireduser beam (i.e., in a different beam coverage area). A third gateway(GW3) is configured to communicate via two different paired beams, andno loopback beam. For example, GW3 is located away from user terminals110. Two ports of a fifth feed (315 e-1 and 215 e-2), two ports of asixth feed (315 f-1 and 215 f-2), and a third paired-beam transponder310 c are used to support GW3 communications with one group of userterminals 110 (U5) in one paired user beam. The other two ports of thefifth feed (315 e-3 and 215 e-4), two ports of a seventh feed (315 g-1and 215 g-2), and a fourth paired-beam transponder 310 d are used tosupport GW3 communications with another group of user terminals 110 (U6)in another paired user beam. While a particular configuration (e.g.,order and number) of loopback transponders 210 and paired-beamtransponders 310 is shown, many configurations are possible withoutdeparting from the scope of embodiments.

FIGS. 1-4 illustrate various embodiments of satellite communicationssystems and related components and architectures for effectuating eitheror both of loopback communications and paired-beam communications.Implementations described above provide a number of features, including,for example, permitting flexible assignment of forward-channel andreturn-channel capacity, permitting spectrum reuse across certain beamsand between gateway and user terminals, and similar transponderarchitectures between loopback and paired-beam types. Some embodimentsprovide further features supporting use of one or more utility gatewayterminals 165 (e.g., alternate gateway terminals 165) in the event thatone or more gateway terminals 165 becomes non-operational. For example,in the illustrative embodiment of FIG. 4, two groups of user terminals110 (i.e., U1 and U3) rely on the first gateway terminal 165 (GW1) toservice their communications. If GW1 “goes down” (e.g., becomesnon-operational due to rain fade, equipment malfunction, or for anyother reason), it can be desirable to effectively switch in a designatedutility gateway in place of the down gateway. FIGS. 5-8B illustratevarious embodiments that support utility gateway functionality.

Turning to FIG. 5, an illustrative architecture 500 is shown including apaired-beam transponder 310 that includes utility gateway support,according to various embodiments. The illustrated paired-beamtransponder architecture 500 is designed to select which of two gatewayterminals 165 to use as the paired-beam gateway for a particular groupof user terminals 110. In alternative embodiments, the selection can bebetween more than two gateway terminals 165 (e.g., to support multipleutility gateways or for any other suitable reason). The selectionbetween a “normal” gateway terminal 165 and a utility gateway terminal165 is performed by any suitable switching components (depicted asutility select switches 520 a and 520 b), such as electrical,electromechanical, and/or other switches. For example, a remote signalfrom a ground network component (e.g., a gateway or other component) candirect the utility select switches 520 to toggle between a “normal” modeand a “utility” mode. As illustrated, when the switches are in normalmode (indicated as the solid-line path in each utility select switch520), the signal path is effectively that of the paired-beamtransponders described above (the components that make up the normalmode transponder are indicated as paired-beam transponder 310). Whilethe components of the paired-beam transponder 310 are illustratedsubstantially as shown in FIG. 3A, other embodiments of a normal modearchitecture can be used (e.g., the embodiment illustrated in FIG. 3B orsome other architecture) without departing from the scope ofembodiments.

In utility mode, the utility select switches 520 are toggled to theirdashed-line configurations, effectively switching out the normal gatewaysignal received via feed 215 b and switching in a utility gateway signalreceived via feed 215 c (e.g., on a now-paired utility gateway beam505). The gateway terminal 165 in communication with the satellite 105via the utility gateway beam 505 can be a gateway terminal 165 that isotherwise in use for other communications or a gateway terminal 165designated for use as a utility gateway. For example, the utilitygateway terminal 165 can be a separate antenna on a gateway terminal 165having other antenna used for “normal” communications, a separatededicated gateway terminal 165 in a separate location, etc.

The utility gateway feed 215 c can be coupled with its own inputamplifier 220 c (e.g., and its own input attenuator 323 b, asappropriate). This can make the utility gateway signal path through thepaired-beam architecture 500 look almost identical to the normal gatewaysignal path through the paired-beam transponder 310. Accordingly some orall of the other processing components (e.g., the input combiner 325,the down-converter 230, the channel filter 240, the output amplifier250, and the output coupler 355 can be used without adding components orappreciably altering that portion of the architecture.

In some implementations, two “N:1” switches 510 are added to the utilitygateway signal path (e.g., between the input amplifier 220 c and theinput attenuator 323 and/or the input-side utility select switch 520 a).The N:1 switches 510 permit a single additional utility gateway feed 215c to act as an alternative gateway for any of up to N normal gatewayterminals 165. For example, the utility gateway feed 215 c is coupledwith the input (“1”) side of a 20:1 switch (as N:1 switch 510 a), andeach of twenty normal gateway terminals 165 is coupled to the output(“20”) side of the switch. When a third normal gateway terminal 165becomes non-operational, the N:1 switches 510 effectively couple theutility gateway feed 215 c with the input signal path for thepaired-beam transponder 310 that normally services the non-operationalthird gateway terminal 165, and the utility select switches 520 switchinto utility mode. The additional outputs of N:1 switch 510 a and theadditional inputs of N:1 switch 510 b can be coupled with otherpaired-beam transponders 310 that service the other gateway terminals165. In alternative embodiments, two or more utility gateway terminals165 are supported. In some such embodiments, the utility select switches520 are configured to switch among more than two potential gateway inputsignal paths. In other such embodiments, the N:1 switches 510 areimplemented as N:M switches, supporting up to M utility gatewayterminals 165 as alternates for up to N normal gateway terminals 165.

For the sake of illustration, embodiments, like those described withreference to FIG. 5, can be used to implement various methods. Whenoperating in normal mode, the operation of embodiments of FIG. 5 can besimilar to those of FIGS. 3A or 3B. An illustrative method begins byreceiving an indication that the first gateway terminal isnon-operational. In response to receiving the indication, thepaired-beam transponder can switch to a utility mode. In the utilitymode, a user uplink signal is received by the paired-beam transponderfrom a group of user terminals via the paired user beam on the uplinkfrequency band, and a utility gateway uplink signal is received from asecond gateway terminal via a utility gateway beam on the uplinkfrequency band. The utility gateway uplink signal and the user uplinksignal can be amplified and combined into a combined input signal, andthe combined input signal can be converted to a combined output signalat a downlink frequency band that is different from the uplink frequencyband. The combined output signal can be transmitted to the secondgateway terminal via the utility gateway beam on the downlink frequencyband. The combined output signal can be transmitted to the group of userterminals via the paired user beam on the downlink frequency band.

FIGS. 6A and 6B show two configurations of an alternate illustrativearchitecture of a paired-beam transponder 600 that includes utilitygateway support, according to various embodiments. The illustratedpaired-beam transponder 600 is designed to select which of two gatewayterminals 165 to use as the paired-beam gateway for a particular groupof user terminals 110 using a “baseball switch” 620. As used herein, a“baseball switch” can be any suitable type of signal switch, including,for example, an electromagnetic “C” switch, radiofrequency “R” or “T”switch, solid-state switch, ferrite switch, etc. The solid signal pathindicates the active signal path (e.g., normal mode using the normalpaired gateway beam 305 b input signal is shown in FIG. 6A) with thebaseball switch 620 in its illustrated configuration. The dashed signalpath indicates an inactive signal path (e.g., the input signal pathcoming from the utility gateway feed 215 c is not currently being usedin the configuration of FIG. 6A) with the baseball switch 620 in itsillustrated configuration. When the baseball switch 620 is in the normalmode configuration illustrated in FIG. 6A, the architecture of thepaired-beam transponder 600 is effectively that of the paired-beamtransponder 310 a of FIG. 3A and the normal mode configuration of thetransponder architecture 500 of FIG. 5. For example, the normal gatewayinput signal and user input signals are received at respective feeds215, amplified and combined by input components (e.g., respective inputamplifiers 220, an input combiner 325, an input attenuator (not shown),etc.), processed by filter block and/or other components (e.g., adown-converter 230, a channel filter 240, etc.), and prepared for outputby output components (e.g., an output amplifier 250, an output coupler355, etc.). Other embodiments of the normal mode architecture can beused without departing from the scope of embodiments.

The utility components of the architecture are described with referenceto FIG. 6B. In FIG. 6B, the baseball switch 620 is in its utilityconfiguration. As shown by the solid and dashed signal paths, the normalgateway signal path is now inactive, and the utility gateway signal pathis now active. The user input signal is received via the paired userbeam 305 a at the user feed 215 a and is amplified by input amplifier220 a. The signal can then be passed through the input combiner 325,which effectively acts as a pass-through (though it may alter the signalto some extent) as there is no normal gateway input signal in this statewith which to combine the user input signal (i.e., it is assumed that nosignal is being received from the non-operational gateway terminal 165).The signal then passes through the baseball switch 620 to a “2:N” switch610. The 2:N switch 610 can include any components of one or moreswitches configured to couple each of two inputs with any of N outputs.The 2:N switch 610 allows the utility gateway feed 215 c to be switchedinto a paired-beam transponder 600 associated with any of N potentiallynon-operational gateway terminals 165. Similarly, the utility gatewayinput signal is received via the now-paired utility gateway beam 505 atthe utility gateway feed 215 c, is amplified by input amplifier 220 c,and is passed to the 2:N switch 610.

Rather than combining the user and utility gateway signals (e.g., as inFIG. 5), each signal follows a respective (e.g., substantiallyidentical) signal processing path. For example, the amplified usersignal is processed by a set of utility filter block and/or othercomponents (e.g., down-converter 230 b and channel filter 240 b), andprepared for output to the utility gateway terminal 165 by a utilityoutput amplifier 250 b. The processed user signal can be communicated tothe utility gateway terminal 165 via the utility gateway feed 215 c andthe now-paired utility gateway beam 505. Similarly, the amplifiedutility gateway signal is processed by the set of normal filter blockand/or other components (e.g., down-converter 230 a and channel filter240 a), and prepared for output to the user terminals 110 by the normaloutput amplifier 250 a. The processed utility gateway signal can becommunicated to the user terminals 110 via the user feed 215 a and thepaired user beam 305 a.

For the sake of illustration, embodiments, like those described withreference to FIGS. 6A and 6B, can be used to implement various methods.When operating in normal mode, the operation of embodiments of FIGS. 6Aand 6B can be similar to those of FIGS. 3A or 3B. An illustrative methodbegins by receiving an indication that the first gateway terminal isnon-operational and switching to a utility mode in response to receivingthe indication. In the utility mode, a user uplink signal is received bya normal input subsystem (e.g., input amplifier 220 a and input combiner325) from a first group of user terminals via the paired user beam onthe uplink frequency band. A utility gateway uplink signal is receivedby a utility input subsystem (e.g., input amplifier 220 c) from a secondgateway terminal via a utility gateway beam on the uplink frequencyband. The user uplink signal is amplified by the normal input subsystem,and the utility gateway uplink signal is amplified by the utility inputsubsystem. The amplified user uplink signal can be converted to a useroutput signal at the downlink frequency band by a utility frequencytranslation subsystem (e.g., down converter 230 b and channel filter 240b), and the user output signal can be transmitted by a utility outputsubsystem (e.g., output amplifier 250 b) to the second gateway terminalvia the utility gateway beam on the downlink frequency band. Theamplified utility gateway uplink signal can be converted to a utilitygateway output signal at the downlink frequency band by a normalfrequency translation subsystem (e.g., down converter 230 a and channelfilter 240 a), and the utility gateway output signal can be transmittedby a normal output subsystem (e.g., output amplifier 250 a) to the firstgroup of user terminals via the paired user beam on the downlinkfrequency band.

FIGS. 7A and 7B show two configurations of an illustrative architectureof a loopback transponder 700 that includes utility gateway support,according to various embodiments. The illustrated loopback transponder700 is designed to select which of two gateway terminals 165 to use asthe loopback gateway for a particular group of user terminals 110 usinga pair of baseball switches 710. The solid signal path indicates theactive signal path (e.g., normal mode using the loopback beam 205 inputsignal is illustrated in FIG. 7A) with the baseball switches 710 intheir illustrated configuration. The dashed signal path indicates aninactive signal path (e.g., the input signal path coming from theutility gateway feed 215 b is not currently being used in theconfiguration illustrated in FIG. 7A) with the baseball switches 710 intheir illustrated configuration. When the baseball switches 710 are inthe normal mode configuration illustrated in FIG. 7A, the architectureof the loopback transponder 700 is effectively that of the loopbacktransponder 210 of FIG. 2. When the baseball switches 710 are in theutility configuration illustrated in FIG. 7B, the architecture of theloopback transponder 700 is effectively that of the paired-beamtransponder 310 a of FIG. 3A.

For example, according to the active signal path of FIG. 7A, the normalgateway input signal and user input signals are both received at feed215 a, amplified by an input amplifier 220 a, passed through theinput-side baseball switch 710 a to filter block and/or other components(e.g., a down-converter 230, a channel filter 240, etc.), prepared foroutput by output amplifier 250, and passed to the feed 215 a fortransmission back over the loopback beam 205. Other embodiments of thenormal mode architecture can be used without departing from the scope ofembodiments. The active signal path shown in FIG. 7B includes separate(i.e., paired in utility mode) user and gateway beams and respectivefeeds 215. Embodiments receive the user input signal via the loopbackbeam 205 and the first feed 215 a, and receive the utility gatewaysignal via the utility gateway beam 505 and a utility gateway feed 215b. Both signals are amplified by respective input amplifiers 220 andpassed (e.g., directly for the gateway input signal, and through theinput-side baseball switch 710 a for the user input signal) to an inputcombiner 325. In some embodiments, as described above, N:1 switches 510can be used to facilitate selection between the utility gateway signalpath and the loopback beam 205 associated with any of N potentiallynon-operational gateway terminals 165. The combined signal is passed(e.g., through another path of the input-side baseball switch 710 a) tothe down-converter 230, channel filter 240, and output amplifier 250.The output-side baseball switch 710 b passes the signal through anoutput coupler 355 to further prepare the signal to be sent individually(e.g., at different power levels as set by the directivity of the outputcoupler 355) to the user terminals 110 and the utility gateway terminal165 through their respective feeds 215 and beams. Using the two baseballswitches 710 permits embodiments to share many of the active components(e.g., the down-converter 230, channel filter 240, and output amplifier250), which can save the design from providing dedicated instances ofthose components for the utility gateway signal path.

For the sake of illustration, embodiments, like those described withreference to FIGS. 7A and 7B, can be used to implement various methods.When operating in normal mode, the operation of embodiments of FIGS. 7Aand 7B can be similar to those of FIG. 2. An illustrative method beginsby receiving an indication that the first gateway terminal isnon-operational and switching to a utility mode in response. In theutility mode, a user uplink signal is received by the loopbacktransponder from a group of user terminals via the loopback beam on theuplink frequency band, and a utility gateway uplink signal is receivedfrom a second gateway terminal via a utility gateway beam on the uplinkfrequency band. The utility gateway uplink signal and the user uplinksignal are combined into a combined input signal. The combined inputsignal can be converted to a combined output signal at the downlinkfrequency band. The combined output signal can be transmitted to thesecond gateway terminal via the utility gateway beam on the downlinkfrequency band, and can be transmitted to the group of user terminalsvia the loopback beam on the downlink frequency band.

FIGS. 8A and 8B show two configurations of an alternative illustrativearchitecture of a loopback transponder 800 that includes utility gatewaysupport, according to various embodiments. The illustrated loopbacktransponder 800 is designed to select which of two gateway terminals 165to use as the loopback gateway for a particular group of user terminals110 using a single baseball switch 810. The solid signal path indicatesthe active signal path (e.g., normal mode using the loopback beam 205input signal is illustrated in FIG. 8A) with the baseball switch 810 inits illustrated configuration. The dashed signal path indicates aninactive signal path (e.g., the input signal path coming from theutility gateway feed 215 b is not currently being used in theconfiguration illustrated in FIG. 8A) with the baseball switch 810 inits illustrated configuration. When the baseball switch 810 is in thenormal mode configuration illustrated in FIG. 8A, the architecture ofthe loopback transponder 800 is effectively that of the loopbacktransponder 210 of FIG. 2 or the normal mode configuration of theloopback transponder 700 of FIG. 7A. When the baseball switch 810 is inthe utility configuration illustrated in FIG. 8B, the architecture ofthe loopback transponder 800 is effectively that of the utility modeconfiguration of the paired-beam transponder 600 b of FIG. 6B.

For example, according to the active signal path of FIG. 8A, the normalgateway input signal and user input signals are both received at feed215 a, amplified by an input amplifier 220 a, passed through thebaseball switch 810 to filter block and/or other components (e.g., adown-converter 230, a channel filter 240, etc.), prepared for output byoutput amplifier 250, and passed to the feed 215 a for transmission backover the loopback beam 205. Other embodiments of the normal modearchitecture can be used without departing from the scope ofembodiments. The active signal path shown in FIG. 8B includes separate(i.e., paired in utility mode) user and gateway beams and respectivefeeds 215. Embodiments receive the user signal via the loopback beam 205and the first feed 215 a, and receive the utility gateway signal via theutility gateway beam 505 and a utility gateway feed 215 b. Both signalsare amplified by respective input amplifiers 220. In some embodiments,as described above, the signals can then pass through a “2:N” switch 610to facilitate selection between the utility gateway signal path and theloopback beam 205 associated with any of N potentially non-operationalgateway terminals 165. As shown, the amplified gateway input signal ispassed directly to the 2:N switch 610, and the amplified user inputsignal is passed to the 2:N switch 610 via the baseball switch 810.

Rather than combining the user and utility gateway signals, each signalfollows a respective (e.g., substantially identical) signal processingpath. For example, the amplified user signal is processed by a set ofutility filter block and/or other components (e.g., down-converter 230 band channel filter 240 b), and prepared for output to the utilitygateway terminal 165 by a utility output amplifier 250 b. The processeduser signal can be communicated to the utility gateway terminal 165 viathe utility gateway feed 215 c and the now-paired utility gateway beam505. Similarly, the amplified utility gateway signal is processed by theset of normal filter block and/or other components (e.g., down-converter230 a and channel filter 240 a), and prepared for output to the userterminals 110 by the normal output amplifier 250 a. The processedutility gateway signal can be communicated to the user terminals 110 viathe user feed 215 a and the loopback beam 205.

For the sake of illustration, embodiments, like those described withreference to FIGS. 8A and 8B, can be used to implement various methods.When operating in normal mode, the operation of embodiments of FIGS. 8Aand 8B can be similar to those of FIG. 2. An illustrative method beginsby receiving an indication that the first gateway terminal isnon-operational and switching to a utility mode in response. In theutility mode, a user uplink signal is received by a normal inputsubsystem (e.g., input amplifier 220 a) from a group of user terminalsvia the loopback beam on the uplink frequency band, and a utilitygateway uplink signal is received by a utility input subsystem (e.g.,input amplifier 220 b) from a second gateway terminal via a utilitygateway beam on the uplink frequency band. The user uplink signal isamplified by the normal input subsystem, and the utility gateway uplinksignal is amplified by the utility input subsystem. The amplified useruplink signal can be converted to a user output signal at the downlinkfrequency band by a utility filter subsystem (e.g., down converter 230 band channel filter 240 b), and the user output signal can be transmittedby a utility output subsystem (e.g., output amplifier 250 b) to thesecond gateway terminal via the utility gateway beam on the downlinkfrequency band. The amplified utility gateway uplink signal can beconverted to a utility gateway output signal at the downlink frequencyband by the normal filter subsystem (e.g., down converter 230 a andchannel filter 240 a), and the utility gateway output signal can betransmitted by the normal output subsystem (e.g., output amplifier 250a) to the group of user terminals via the paired user beam on thedownlink frequency band.

As described above, embodiments of the loopback and paired-beamtransponders are designed to use similar components. Accordingly,redundancy rings and/or other architectures can be used to provideredundant active components (e.g., input amplifiers 320, down-converters330, channel filters 340, output amplifiers 350, etc.) for either orboth types of transponder. For example, in a satellite architecture thatincludes both types of transponder, like the one illustrated in FIG. 4,a set of redundant components can be used across multiple transpondersof different types.

In some embodiments, some or all of the spare components can bedesignated as “active spares.” Implementations of loopback transponders310 and paired-beam transponders 410 that have utility gateway supportcan be implemented with spare components that are designated for use bythe utility gateway signal path, when operating in utility mode, asdescribed above. For example, FIGS. 6A, 6B, 8A, and 8B show embodimentsof transponders for which, in utility mode, a set of active utilitycomponents is switched into a signal path of the transponder. Some orall of these utility components can be implemented as an active sparecomponent: when a transponder is operating in normal mode, the activespare component is available (e.g., in a redundancy ring) for use as aspare component by being switched into a normal signal path of thetransponder; and when the transponder is operating in utility mode, theactive spare component is available (e.g., in the same redundancy ring,via a dedicated signal path) for use as a utility component by beingswitched into a utility signal path. In some embodiments, the sparecomponents are arranged to provide components that are usable only asnormal spares (they do not have a dedicated signal path for use by autility gateway) for normal components (they can only be switched intothe normal signal path of a transponder), as active spares (they have adedicated signal path for use by a utility gateway), as normal sparesfor active spares (they can be switched into the utility signal path ofa transponder when the active spare fails), etc.

The methods disclosed herein include one or more actions for achievingthe described method. The method and/or actions can be interchanged withone another without departing from the scope of the claims. In otherwords, unless a specific order of actions is specified, the order and/oruse of specific actions can be modified without departing from the scopeof the claims.

The various operations of methods and functions of certain systemcomponents described above can be performed by any suitable meanscapable of performing the corresponding functions. These means can beimplemented, in whole or in part, in hardware. Thus, they can includeone or more Application Specific Integrated Circuits (ASICs) adapted toperform a subset of the applicable functions in hardware. Alternatively,the functions can be performed by one or more other processing units (orcores), on one or more integrated circuits (ICs). In other embodiments,other types of integrated circuits can be used (e.g.,Structured/Platform ASICs, Field Programmable Gate Arrays (FPGAs), andother Semi-Custom ICs), which can be programmed. Each can also beimplemented, in whole or in part, with instructions embodied in acomputer-readable medium, formatted to be executed by one or moregeneral or application specific controllers. Embodiments can also beconfigured to support plug-and-play functionality (e.g., through theDigital Living Network Alliance (DLNA) standard), wireless networking(e.g., through the 802.11 standard), etc.

The steps of a method or algorithm or other functionality described inconnection with the present disclosure, can be embodied directly inhardware, in a software module executed by a processor, or in acombination of the two. A software module can reside in any form oftangible storage medium. Some examples of storage media that can be usedinclude random access memory (RAM), read only memory (ROM), flashmemory, EPROM memory, EEPROM memory, registers, a hard disk, a removabledisk, a CD-ROM and so forth. A storage medium can be coupled to aprocessor such that the processor can read information from, and writeinformation to, the storage medium. In the alternative, the storagemedium can be integral to the processor.

A software module can be a single instruction, or many instructions, andcan be distributed over several different code segments, among differentprograms, and across multiple storage media. Thus, a computer programproduct can perform operations presented herein. For example, such acomputer program product can be a computer readable tangible mediumhaving instructions tangibly stored (and/or encoded) thereon, theinstructions being executable by one or more processors to perform theoperations described herein. The computer program product can includepackaging material. Software or instructions can also be transmittedover a transmission medium. For example, software can be transmittedfrom a website, server, or other remote source using a transmissionmedium such as a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technology such as infrared, radio,or microwave.

Other examples and implementations are within the scope and spirit ofthe disclosure and appended claims. For example, features implementingfunctions can also be physically located at various positions, includingbeing distributed such that portions of functions are implemented atdifferent physical locations. Also, as used herein, including in theclaims, “or” as used in a list of items prefaced by “at least one of”indicates a disjunctive list such that, for example, a list of “at leastone of A, B, or C” means A or B or C or AB or AC or BC or ABC (i.e., Aand B and C). Further, the term “exemplary” does not mean that thedescribed example is preferred or better than other examples.

Various changes, substitutions, and alterations to the techniquesdescribed herein can be made without departing from the technology ofthe teachings as defined by the appended claims. Moreover, the scope ofthe disclosure and claims is not limited to the particular aspects ofthe process, machine, manufacture, composition of matter, means,methods, and actions described above. Processes, machines, manufacture,compositions of matter, means, methods, or actions, presently existingor later to be developed, that perform substantially the same functionor achieve substantially the same result as the corresponding aspectsdescribed herein can be utilized. Accordingly, the appended claimsinclude within their scope such processes, machines, manufacture,compositions of matter, means, methods, or actions.

What is claimed is:
 1. A method for satellite communications, the methodcomprising: receiving, via a satellite transponder of a satellite, afirst combined uplink signal in an uplink frequency band during a firsttime, the first combined uplink signal having a first ratio offorward-channel traffic to return-channel traffic according to aflexible allocation of forward-channel and return-channel portions ofthe uplink frequency band; transmitting a first combined downlink signalduring the first time, the first combined downlink signal correspondingto the first combined uplink signal translated to a downlink frequencyband via a frequency translator of the satellite transponder; receiving,via the satellite transponder, a second combined uplink signal in theuplink frequency band during a second time, the second combined uplinksignal having a second ratio of the forward-channel traffic to thereturn-channel traffic according to the flexible allocation offorward-channel and return-channel portions of the uplink frequencyband, wherein the second ratio is different than the first ratio; andtransmitting a second combined downlink signal during the second time,the second combined downlink signal corresponding to the second combineduplink signal translated to the downlink frequency band via thefrequency translator of the satellite transponder.
 2. The method ofclaim 1, wherein: the receiving the first combined uplink signal duringthe first time comprises: receiving a first gateway uplink signal in theuplink frequency band from a gateway terminal; and concurrently withreceiving the first gateway uplink signal, receiving a first user uplinksignal in the uplink frequency band from a plurality of user terminals;combining the first gateway uplink signal and the first user uplinksignal to generate the first combined uplink signal; and thetransmitting the first combined downlink signal during the first timecomprises: transmitting the first combined downlink signal to the firstgateway terminal and to the plurality of user terminals.
 3. The methodof claim 2, wherein the first gateway uplink signal and the first useruplink signal are combined non-coherently.
 4. The method of claim 2,wherein: the forward-channel traffic is transmitted in the uplinkfrequency band by the gateway terminal via the first gateway uplinksignal, and received in the downlink frequency band by plurality of userterminals via the first combined downlink signal; and the return-channeltraffic is transmitted in the uplink frequency band by the plurality ofuser terminals via the first user uplink frequency band, and received inthe downlink frequency band by the gateway terminal via the firstcombined downlink signal.
 5. The method of claim 2, wherein: thereceiving the first gateway uplink signal and the receiving the firstuser uplink signal is via one or more feeds of the satellite; and thetransmitting the first combined downlink signal is via the one or morefeeds of the satellite.
 6. The method of claim 5, wherein: the one ormore feeds is a loopback feed having a loopback beam coverage area; thegateway terminal and the plurality of user terminals are located in theloopback beam coverage area of the loopback feed; the receiving thefirst gateway uplink signal and the first user uplink signal is via theloopback feed; the combining is via the loopback feed to generate thefirst combined uplink signal; and the transmitting the first combineddownlink signal is via the loopback feed.
 7. The method of claim 5,wherein: the one or more feeds includes a first feed having a first spotbeam coverage area and a second feed having a second spot beam coveragearea; the gateway terminal is located in the first spot beam coveragearea of the first feed; the plurality of user terminals are located inthe second spot beam coverage area of the second feed of the satellite;the receiving the first gateway uplink signal is via the first feed, andthe receiving the first user uplink signal is via the second feed; thecombining is via an input subsystem of the satellite transponder coupledto the first and second feeds to generate the first combined uplinksignal; and the transmitting the first combined downlink signal to thefirst gateway terminal is via the first feed and the transmitting thefirst combined downlink signal to the plurality of user terminals is viathe second feed.
 8. The method of claim 7, further comprising:attenuating, via an attenuator, the first gateway uplink signal relativeto the first user uplink signal prior to the combining.
 9. The method ofclaim 7, further comprising: amplifying the first gateway uplink signalvia a first input amplifier of the input subsystem; and amplifying thefirst user uplink signal via a second input amplifier of the inputsubsystem, and wherein the combining is via an input combiner of theinput subsystem that combines the amplified first gateway uplink signaland the amplified first user uplink signal to generate the firstcombined uplink signal.
 10. The method of claim 7, wherein the combiningis via an input combiner of the input system that combines the firstgateway uplink signal obtained from the first feed and the first useruplink signal obtained from the second feed to generate the firstcombined uplink signal.
 11. The method of claim 10, further comprisingamplifying the first combined uplink signal obtained from the inputcombiner via an input amplifier.
 12. The method of claim 7, furthercomprising providing the first combined downlink signal to the first andsecond feeds via an output coupler of an output subsystem of thesatellite transponder.
 13. The method of claim 5, wherein the satellitetransponder comprises an input subsystem between the frequencytranslator and the one or more feeds of the satellite, and an outputsubsystem between the frequency translator and the one or more feeds ofthe satellite.
 14. The method of claim 1, wherein the flexibleallocation defines a first one or more sub-bands of the uplink frequencyband and a first one or more sub-bands of the downlink frequency band tothe forward-channel portions, and defines a second one or more sub-bandsof the uplink frequency band and a second one or more sub-bands of thedownlink frequency band to the return-channel portions.
 15. The methodof claim 1, wherein the flexible allocation of forward-channel andreturn-channel portions of the uplink frequency band is according to aspread-spectrum scheme.
 16. The method of claim 1, wherein the downlinkfrequency band does not overlap the uplink frequency band.
 17. Themethod of claim 1, further comprising: operating one or more switchingcomponents of the satellite in a normal mode during the first and secondtimes; and operating the one or more switching components of thesatellite in a utility mode during a third time.
 18. The method of claim17, wherein: the normal mode couples the satellite transponder to one ormore feeds of the satellite; and the utility mode further couples thesatellite transponder to a utility gateway feed of the satellite. 19.The method of claim 18, wherein the utility mode further decouples thesatellite transponder from at least one of the one or more feeds of thesatellite.
 20. The method of claim 17, wherein the one or more switchingcomponents comprises: a first switching component to selectively couplethe utility gateway feed to an input subsystem of the satellitetransponder; and a second switching component to selectively couple theutility gateway feed to an output subsystem of the satellitetransponder.
 21. The method of claim 17, wherein: operating thesatellite transponder in the normal mode during the first and secondtimes comprises: receiving, during the first time, the first combineduplink signal comprising a first gateway uplink signal in the uplinkfrequency band from a gateway terminal and a first user uplink signal inthe uplink frequency band from a plurality of user terminals;transmitting, during the first time, the first combined downlink signalto the first gateway terminal and to the plurality of user terminals;receiving, during the second time, the second combined downlink signalcomprising a second gateway uplink signal in the uplink frequency bandfrom the gateway terminal and a second user uplink signal in the uplinkfrequency band from the plurality of user terminals; transmitting,during the second time, the second combined downlink signal to the firstgateway terminal and to the plurality of user terminals; and operatingthe satellite transponder in the utility mode during the third timecomprises: receiving a utility gateway uplink signal in the uplinkfrequency band from a utility gateway terminal and a third user uplinksignal in the uplink frequency band from the plurality of userterminals; transmitting a utility gateway downlink signal to the utilitygateway terminal, the utility gateway downlink signal corresponding tothe third user uplink signal translated to the downlink frequency band;and transmitting a user downlink signal to the plurality of userterminals, the user downlink signal corresponding to the utility gatewayuplink signal translated to the downlink frequency band.
 22. The methodof claim 21, wherein: the gateway terminal and the plurality of userterminals are located in a loopback beam coverage area of a loopbackfeed of the satellite; the utility gateway terminal is located outsidethe loopback beam coverage area; the receiving the first combined uplinksignal, the transmitting the first combined downlink signal, thereceiving the second combined uplink signal, the transmitting the secondcombined downlink signal, and the transmitting the user downlink signalare each via the loopback feed; and the receiving the utility gatewayuplink signal and the transmitting the utility gateway downlink signalare each via a utility gateway feed.
 23. The method of claim 21, furthercomprising: receiving, via the satellite transponder, a third combineduplink signal comprising the utility gateway uplink signal and the thirduser uplink signal; translating the third combined uplink signal to forma third combined downlink signal via the frequency translator of thesatellite transponder, the third combined downlink signal comprising theutility gateway downlink signal and the user downlink signal; andwherein transmitting the utility gateway downlink signal andtransmitting the user downlink signal comprises transmitting the thirdcombined downlink signal to the utility gateway terminal and to theplurality of user terminals
 24. The method of claim 21, wherein: thefrequency translator is a first frequency translator; the third useruplink signal is translated to the downlink frequency band via the firstfrequency translator; and the utility gateway uplink signal translatedto the downlink frequency band via a second frequency translator of thesatellite transponder.